1 #!/usr/bin/env python 2 3 """ 4 Import logic. 5 6 Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 7 2014, 2015, 2016 Paul Boddie <paul@boddie.org.uk> 8 9 This program is free software; you can redistribute it and/or modify it under 10 the terms of the GNU General Public License as published by the Free Software 11 Foundation; either version 3 of the License, or (at your option) any later 12 version. 13 14 This program is distributed in the hope that it will be useful, but WITHOUT 15 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS 16 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more 17 details. 18 19 You should have received a copy of the GNU General Public License along with 20 this program. If not, see <http://www.gnu.org/licenses/>. 21 """ 22 23 from errors import ProgramError 24 from os.path import exists, extsep, getmtime, join 25 from os import listdir, makedirs, remove 26 from common import init_item, readfile, writefile 27 from modules import CachedModule 28 from referencing import Reference 29 import inspector 30 import sys 31 32 class Importer: 33 34 "An import machine, searching for and loading modules." 35 36 def __init__(self, path, cache=None, verbose=False): 37 38 """ 39 Initialise the importer with the given search 'path' - a list of 40 directories to search for Python modules. 41 42 The optional 'cache' should be the name of a directory used to store 43 cached module information. 44 45 The optional 'verbose' parameter causes output concerning the activities 46 of the object to be produced if set to a true value (not the default). 47 """ 48 49 self.path = path 50 self.cache = cache 51 self.verbose = verbose 52 53 # Module importing queue, required modules, removed modules and active 54 # modules in the final program. 55 56 self.to_import = set() 57 self.required = set(["__main__"]) 58 self.removed = {} 59 self.modules = {} 60 61 # Module relationships and invalidated cached modules. 62 63 self.accessing_modules = {} 64 self.invalidated = set() 65 66 # Basic program information. 67 68 self.objects = {} 69 self.classes = {} 70 self.function_parameters = {} 71 self.function_defaults = {} 72 self.function_locals = {} 73 self.function_targets = {} 74 self.function_arguments = {} 75 76 # Unresolved names. 77 78 self.missing = set() 79 80 # Derived information. 81 82 self.subclasses = {} 83 84 # Attributes of different object types. 85 86 self.all_class_attrs = {} 87 self.all_instance_attrs = {} 88 self.all_instance_attr_constants = {} 89 self.all_combined_attrs = {} 90 self.all_module_attrs = {} 91 self.all_shadowed_attrs = {} 92 93 # References to external names and aliases within program units. 94 95 self.all_name_references = {} 96 self.all_initialised_names = {} 97 self.all_aliased_names = {} 98 99 # General attribute accesses. 100 101 self.all_attr_accesses = {} 102 self.all_const_accesses = {} 103 self.all_attr_access_modifiers = {} 104 105 # Constant literals and values. 106 107 self.all_constants = {} 108 self.all_constant_values = {} 109 110 self.make_cache() 111 112 def make_cache(self): 113 if self.cache and not exists(self.cache): 114 makedirs(self.cache) 115 116 def check_cache(self, details): 117 118 """ 119 Check whether the cache applies for the given 'details', invalidating it 120 if it does not. 121 """ 122 123 recorded_details = self.get_cache_details() 124 125 if recorded_details != details: 126 self.remove_cache() 127 128 writefile(self.get_cache_details_filename(), details) 129 130 def get_cache_details_filename(self): 131 132 "Return the filename for the cache details." 133 134 return join(self.cache, "$details") 135 136 def get_cache_details(self): 137 138 "Return details of the cache." 139 140 details_filename = self.get_cache_details_filename() 141 142 if not exists(details_filename): 143 return None 144 else: 145 return readfile(details_filename) 146 147 def remove_cache(self): 148 149 "Remove the contents of the cache." 150 151 for filename in listdir(self.cache): 152 remove(join(self.cache, filename)) 153 154 def to_cache(self): 155 156 "Write modules to the cache." 157 158 if self.cache: 159 for module_name, module in self.modules.items(): 160 module.to_cache(join(self.cache, module_name)) 161 162 # Object retrieval and storage. 163 164 def get_object(self, name): 165 166 """ 167 Return a reference for the given 'name' or None if no such object 168 exists. 169 """ 170 171 return self.objects.get(name) 172 173 def set_object(self, name, value=None): 174 175 "Set the object with the given 'name' and the given 'value'." 176 177 if isinstance(value, Reference): 178 ref = value.alias(name) 179 else: 180 ref = Reference(value, name) 181 182 self.objects[name] = ref 183 184 # Identification of both stored object names and name references. 185 186 def identify(self, name): 187 188 "Identify 'name' using stored object and external name records." 189 190 return self.objects.get(name) or self.all_name_references.get(name) 191 192 # Indirect object retrieval. 193 194 def get_attributes(self, ref, attrname): 195 196 """ 197 Return attributes provided by 'ref' for 'attrname'. Class attributes 198 may be provided by instances. 199 """ 200 201 kind = ref.get_kind() 202 if kind == "<class>": 203 ref = self.get_class_attribute(ref.get_origin(), attrname) 204 return ref and set([ref]) or set() 205 elif kind == "<instance>": 206 return self.get_combined_attributes(ref.get_origin(), attrname) 207 elif kind == "<module>": 208 ref = self.get_module_attribute(ref.get_origin(), attrname) 209 return ref and set([ref]) or set() 210 else: 211 return set() 212 213 def get_class_attribute(self, object_type, attrname): 214 215 "Return from 'object_type' the details of class attribute 'attrname'." 216 217 attrs = self.all_class_attrs.get(object_type) 218 attr = attrs and attrs.get(attrname) 219 return attr and self.get_object(attr) 220 221 def get_instance_attributes(self, object_type, attrname): 222 223 """ 224 Return from 'object_type' the details of instance attribute 'attrname'. 225 """ 226 227 consts = self.all_instance_attr_constants.get(object_type) 228 attrs = set() 229 for attr in self.all_instance_attrs[object_type].get(attrname, []): 230 attrs.add(consts and consts.get(attrname) or Reference("<var>", attr)) 231 return attrs 232 233 def get_combined_attributes(self, object_type, attrname): 234 235 """ 236 Return from 'object_type' the details of class or instance attribute 237 'attrname'. 238 """ 239 240 ref = self.get_class_attribute(object_type, attrname) 241 refs = ref and set([ref]) or set() 242 refs.update(self.get_instance_attributes(object_type, attrname)) 243 return refs 244 245 def get_module_attribute(self, object_type, attrname): 246 247 "Return from 'object_type' the details of module attribute 'attrname'." 248 249 if attrname in self.all_module_attrs[object_type]: 250 return self.get_object("%s.%s" % (object_type, attrname)) 251 else: 252 return None 253 254 # Convenience methods for deducing which kind of object provided an 255 # attribute. 256 257 def get_attribute_provider(self, ref, attrname): 258 259 """ 260 Return the kind of provider of the attribute accessed via 'ref' using 261 'attrname'. 262 """ 263 264 kind = ref.get_kind() 265 266 if kind in ["<class>", "<module>"]: 267 return kind 268 else: 269 return self.get_instance_attribute_provider(ref.get_origin(), attrname) 270 271 def get_instance_attribute_provider(self, object_type, attrname): 272 273 """ 274 Return the kind of provider of the attribute accessed via an instance of 275 'object_type' using 'attrname'. 276 """ 277 278 if self.get_class_attribute(object_type, attrname): 279 return "<class>" 280 else: 281 return "<instance>" 282 283 # Module management. 284 285 def queue_module(self, name, accessor, required=False): 286 287 """ 288 Queue the module with the given 'name' for import from the given 289 'accessor' module. If 'required' is true (it is false by default), the 290 module will be required in the final program. 291 """ 292 293 if not self.modules.has_key(name): 294 self.to_import.add(name) 295 296 if required: 297 self.required.add(name) 298 299 init_item(self.accessing_modules, name, set) 300 self.accessing_modules[name].add(accessor.name) 301 302 def get_modules(self): 303 304 "Return all modules known to the importer." 305 306 return self.modules.values() 307 308 def get_module(self, name): 309 310 "Return the module with the given 'name'." 311 312 if not self.modules.has_key(name): 313 return None 314 315 return self.modules[name] 316 317 # Program operations. 318 319 def initialise(self, filename, reset=False): 320 321 """ 322 Initialise a program whose main module is 'filename', resetting the 323 cache if 'reset' is true. Return the main module. 324 """ 325 326 if reset: 327 self.remove_cache() 328 self.check_cache(filename) 329 330 # Load the program itself. 331 332 m = self.load_from_file(filename) 333 334 # Load any queued modules. 335 336 while self.to_import: 337 for name in list(self.to_import): # avoid mutation issue 338 self.load(name) 339 340 # Resolve dependencies between modules. 341 342 self.resolve() 343 344 # Record the type of all classes. 345 346 self.type_ref = self.get_object("__builtins__.type") 347 348 # Resolve dependencies within the program. 349 350 for module in self.modules.values(): 351 module.complete() 352 353 # Remove unneeded modules. 354 355 all_modules = self.modules.items() 356 357 for name, module in all_modules: 358 if name not in self.required: 359 module.unpropagate() 360 del self.modules[name] 361 self.removed[name] = module 362 363 # Collect redundant objects. 364 365 for module in self.removed.values(): 366 module.collect() 367 368 # Assert module objects where aliases have been removed. 369 370 for name in self.required: 371 if not self.objects.has_key(name): 372 self.objects[name] = Reference("<module>", name) 373 374 return m 375 376 def finalise(self): 377 378 """ 379 Finalise the inspected program, returning whether the program could be 380 finalised. 381 """ 382 383 if self.missing: 384 return False 385 386 self.finalise_classes() 387 self.to_cache() 388 self.set_class_types() 389 self.define_instantiators() 390 self.collect_constants() 391 392 return True 393 394 # Supporting operations. 395 396 def resolve(self): 397 398 "Resolve dependencies between modules." 399 400 self.waiting = {} 401 self.depends = {} 402 403 for module in self.modules.values(): 404 405 # Resolve all deferred references in each module. 406 407 for ref in module.deferred: 408 found = self.find_dependency(ref) 409 if not found: 410 self.missing.add((module.name, ref.get_origin())) 411 412 # Record the resolved names and identify required modules. 413 414 else: 415 # Find the providing module of this reference. 416 # Where definitive details of the origin cannot be found, 417 # identify the provider using the deferred reference. 418 # NOTE: This may need to test for static origins. 419 420 provider = self.get_module_provider(found.unresolved() and ref or found) 421 ref.mutate(found) 422 423 # Record any external dependency. 424 425 if provider and provider != module.name: 426 427 # Record the provider dependency. 428 429 module.required.add(provider) 430 self.accessing_modules[provider].add(module.name) 431 432 # Postpone any inclusion of the provider until this 433 # module becomes required. 434 435 if module.name not in self.required: 436 init_item(self.waiting, module.name, set) 437 self.waiting[module.name].add(provider) 438 439 # Make this module required in the accessing module. 440 441 elif provider not in self.required: 442 self.required.add(provider) 443 if self.verbose: 444 print >>sys.stderr, "Requiring", provider, "for", ref 445 446 # Record a module ordering dependency. 447 448 if not found.static(): 449 init_item(self.depends, module.name, set) 450 self.depends[module.name].add(provider) 451 452 # Check modules again to see if they are now required and should now 453 # cause the inclusion of other modules providing objects to the program. 454 455 for module_name in self.waiting.keys(): 456 self.require_providers(module_name) 457 458 def require_providers(self, module_name): 459 460 """ 461 Test if 'module_name' is itself required and, if so, require modules 462 containing objects provided to the module. 463 """ 464 465 if module_name in self.required and self.waiting.has_key(module_name): 466 for provider in self.waiting[module_name]: 467 if provider not in self.required: 468 self.required.add(provider) 469 if self.verbose: 470 print >>sys.stderr, "Requiring", provider 471 self.require_providers(provider) 472 473 def order_modules(self): 474 475 "Produce a module initialisation ordering." 476 477 self.check_ordering() 478 479 module_names = self.modules.keys() 480 481 # Record the number of modules using or depending on each module. 482 483 usage = {} 484 485 for module_name in module_names: 486 usage[module_name] = 0 487 488 for module_name, depend_names in self.depends.items(): 489 if module_name in module_names: 490 for depend_name in depend_names: 491 if depend_name in module_names: 492 usage[depend_name] += 1 493 494 # Produce an ordering by obtaining exposed modules (required by modules 495 # already processed) and putting them at the start of the list. 496 497 ordered = [] 498 499 while usage: 500 for module_name, n in usage.items(): 501 if n == 0: 502 ordered.insert(0, module_name) 503 module_names = self.depends.get(module_name) 504 505 # Reduce usage of the referenced modules. 506 507 if module_names: 508 for name in module_names: 509 usage[name] -= 1 510 511 del usage[module_name] 512 513 ordered.remove("__main__") 514 ordered.append("__main__") 515 return ordered 516 517 def check_ordering(self): 518 519 "Check the ordering dependencies." 520 521 for module_name, modules in self.depends.items(): 522 for provider in modules: 523 if self.depends.has_key(provider) and module_name in self.depends[provider]: 524 raise ProgramError, "Modules %s and %s may not depend on each other for non-static objects." % (module_name, provider) 525 526 def find_dependency(self, ref): 527 528 "Find the ultimate dependency for 'ref'." 529 530 found = set() 531 while ref and ref.has_kind("<depends>") and not ref in found: 532 found.add(ref) 533 ref = self.identify(ref.get_origin()) 534 return ref 535 536 def get_module_provider(self, ref): 537 538 "Identify the provider of the given 'ref'." 539 540 for ancestor in ref.ancestors(): 541 if self.modules.has_key(ancestor): 542 return ancestor 543 return None 544 545 def finalise_classes(self): 546 547 "Finalise the class relationships and attributes." 548 549 self.derive_inherited_attrs() 550 self.derive_subclasses() 551 self.derive_shadowed_attrs() 552 553 def derive_inherited_attrs(self): 554 555 "Derive inherited attributes for classes throughout the program." 556 557 for name in self.classes.keys(): 558 self.propagate_attrs_for_class(name) 559 560 def propagate_attrs_for_class(self, name, visited=None): 561 562 "Propagate inherited attributes for class 'name'." 563 564 # Visit classes only once. 565 566 if self.all_combined_attrs.has_key(name): 567 return 568 569 visited = visited or [] 570 571 if name in visited: 572 raise ProgramError, "Class %s may not inherit from itself: %s -> %s." % (name, " -> ".join(visited), name) 573 574 visited.append(name) 575 576 class_attrs = {} 577 instance_attrs = {} 578 579 # Aggregate the attributes from base classes, recording the origins of 580 # applicable attributes. 581 582 for base in self.classes[name][::-1]: 583 584 # Get the identity of the class from the reference. 585 586 base = base.get_origin() 587 588 # Define the base class completely before continuing with this 589 # class. 590 591 self.propagate_attrs_for_class(base, visited) 592 class_attrs.update(self.all_class_attrs[base]) 593 594 # Instance attribute origins are combined if different. 595 596 for key, values in self.all_instance_attrs[base].items(): 597 init_item(instance_attrs, key, set) 598 instance_attrs[key].update(values) 599 600 # Class attributes override those defined earlier in the hierarchy. 601 602 class_attrs.update(self.all_class_attrs.get(name, {})) 603 604 # Instance attributes are merely added if not already defined. 605 606 for key in self.all_instance_attrs.get(name, []): 607 if not instance_attrs.has_key(key): 608 instance_attrs[key] = set(["%s.%s" % (name, key)]) 609 610 self.all_class_attrs[name] = class_attrs 611 self.all_instance_attrs[name] = instance_attrs 612 self.all_combined_attrs[name] = set(class_attrs.keys()).union(instance_attrs.keys()) 613 614 def derive_subclasses(self): 615 616 "Derive subclass details for classes." 617 618 for name, bases in self.classes.items(): 619 for base in bases: 620 621 # Get the identity of the class from the reference. 622 623 base = base.get_origin() 624 self.subclasses[base].add(name) 625 626 def derive_shadowed_attrs(self): 627 628 "Derive shadowed attributes for classes." 629 630 for name, attrs in self.all_instance_attrs.items(): 631 attrs = set(attrs.keys()).intersection(self.all_class_attrs[name].keys()) 632 if attrs: 633 self.all_shadowed_attrs[name] = attrs 634 635 def set_class_types(self): 636 637 "Set the type of each class." 638 639 for attrs in self.all_class_attrs.values(): 640 attrs["__class__"] = self.type_ref.get_origin() 641 642 def define_instantiators(self): 643 644 """ 645 Consolidate parameter and default details, incorporating initialiser 646 details to define instantiator signatures. 647 """ 648 649 for cls, attrs in self.all_class_attrs.items(): 650 initialiser = attrs["__init__"] 651 self.function_parameters[cls] = self.function_parameters[initialiser] 652 self.function_defaults[cls] = self.function_defaults[initialiser] 653 654 def collect_constants(self): 655 656 "Get constants from all active modules." 657 658 for module in self.modules.values(): 659 self.all_constants.update(module.constants) 660 661 # Import methods. 662 663 def find_in_path(self, name): 664 665 """ 666 Find the given module 'name' in the search path, returning None where no 667 such module could be found, or a 2-tuple from the 'find' method 668 otherwise. 669 """ 670 671 for d in self.path: 672 m = self.find(d, name) 673 if m: return m 674 return None 675 676 def find(self, d, name): 677 678 """ 679 In the directory 'd', find the given module 'name', where 'name' can 680 either refer to a single file module or to a package. Return None if the 681 'name' cannot be associated with either a file or a package directory, 682 or a 2-tuple from '_find_package' or '_find_module' otherwise. 683 """ 684 685 m = self._find_package(d, name) 686 if m: return m 687 m = self._find_module(d, name) 688 if m: return m 689 return None 690 691 def _find_module(self, d, name): 692 693 """ 694 In the directory 'd', find the given module 'name', returning None where 695 no suitable file exists in the directory, or a 2-tuple consisting of 696 None (indicating that no package directory is involved) and a filename 697 indicating the location of the module. 698 """ 699 700 name_py = name + extsep + "py" 701 filename = self._find_file(d, name_py) 702 if filename: 703 return None, filename 704 return None 705 706 def _find_package(self, d, name): 707 708 """ 709 In the directory 'd', find the given package 'name', returning None 710 where no suitable package directory exists, or a 2-tuple consisting of 711 a directory (indicating the location of the package directory itself) 712 and a filename indicating the location of the __init__.py module which 713 declares the package's top-level contents. 714 """ 715 716 filename = self._find_file(d, name) 717 if filename: 718 init_py = "__init__" + extsep + "py" 719 init_py_filename = self._find_file(filename, init_py) 720 if init_py_filename: 721 return filename, init_py_filename 722 return None 723 724 def _find_file(self, d, filename): 725 726 """ 727 Return the filename obtained when searching the directory 'd' for the 728 given 'filename', or None if no actual file exists for the filename. 729 """ 730 731 filename = join(d, filename) 732 if exists(filename): 733 return filename 734 else: 735 return None 736 737 def load(self, name): 738 739 """ 740 Load the module or package with the given 'name'. Return an object 741 referencing the loaded module or package, or None if no such module or 742 package exists. 743 """ 744 745 # Loaded modules are returned immediately. 746 # Modules may be known but not yet loading (having been registered as 747 # submodules), loading, loaded, or completely unknown. 748 749 module = self.get_module(name) 750 751 if module: 752 return self.modules[name] 753 754 # Otherwise, modules are loaded. 755 756 # Split the name into path components, and try to find the uppermost in 757 # the search path. 758 759 path = name.split(".") 760 path_so_far = [] 761 module = None 762 763 for p in path: 764 765 # Get the module's filesystem details. 766 767 if not path_so_far: 768 m = self.find_in_path(p) 769 elif d: 770 m = self.find(d, p) 771 else: 772 m = None 773 774 path_so_far.append(p) 775 module_name = ".".join(path_so_far) 776 777 if not m: 778 if self.verbose: 779 print >>sys.stderr, "Not found (%s)" % name 780 781 return None # NOTE: Import error. 782 783 # Get the module itself. 784 785 d, filename = m 786 module = self.load_from_file(filename, module_name) 787 788 return module 789 790 def load_from_file(self, filename, module_name=None): 791 792 "Load the module from the given 'filename'." 793 794 if module_name is None: 795 module_name = "__main__" 796 797 module = self.modules.get(module_name) 798 799 if not module: 800 801 # Try to load from cache. 802 803 module = self.load_from_cache(filename, module_name) 804 if module: 805 return module 806 807 # If no cache entry exists, load from file. 808 809 module = inspector.InspectedModule(module_name, self) 810 self.add_module(module_name, module) 811 self.update_cache_validity(module) 812 813 self._load(module, module_name, lambda m: m.parse, filename) 814 815 return module 816 817 def update_cache_validity(self, module): 818 819 "Make 'module' valid in the cache, but invalidate accessing modules." 820 821 accessing = self.accessing_modules.get(module.name) 822 if accessing: 823 self.invalidated.update(accessing) 824 if module.name in self.invalidated: 825 self.invalidated.remove(module.name) 826 827 def source_is_new(self, filename, module_name): 828 829 "Return whether 'filename' is newer than the cached 'module_name'." 830 831 if self.cache: 832 cache_filename = join(self.cache, module_name) 833 return not exists(cache_filename) or \ 834 getmtime(filename) > getmtime(cache_filename) or \ 835 module_name in self.invalidated 836 else: 837 return True 838 839 def load_from_cache(self, filename, module_name): 840 841 "Return a module residing in the cache." 842 843 module = self.modules.get(module_name) 844 845 if not module and not self.source_is_new(filename, module_name): 846 module = CachedModule(module_name, self) 847 self.add_module(module_name, module) 848 849 filename = join(self.cache, module_name) 850 self._load(module, module_name, lambda m: m.from_cache, filename) 851 852 return module 853 854 def _load(self, module, module_name, fn, filename): 855 856 """ 857 Load 'module' for the given 'module_name', and with 'fn' performing an 858 invocation on the module with the given 'filename'. 859 """ 860 861 # Load the module. 862 863 if self.verbose: 864 print >>sys.stderr, module_name in self.required and "Required" or "Loading", module_name, "from", filename 865 fn(module)(filename) 866 867 # Add the module object if not already defined. 868 869 if not self.objects.has_key(module_name): 870 self.objects[module_name] = Reference("<module>", module_name) 871 872 def add_module(self, module_name, module): 873 874 """ 875 Return the module with the given 'module_name', adding a new module 876 object if one does not already exist. 877 """ 878 879 self.modules[module_name] = module 880 if module_name in self.to_import: 881 self.to_import.remove(module_name) 882 883 # vim: tabstop=4 expandtab shiftwidth=4